Locomotion is the general definition of all the movements that cause transferring of the body weight. Normal bipedal gait is the most common human activity that is achieved due to the coordination within changes of mutual body segments displacement and muscles work. Systematic study of walking confirmed its complex nature that apparently seems to be very simple. Current technology involving more sophisticated and advanced instruments permits dynamic recording of many specific gait characteristics. In recent years surface electromyography (EMG) has become an important toll in establishing the role of muscles in the specific activities. The first recording of this electrical activity was made by Marey in 1890, who also introduced the term “electromyography” [1]. This method is a proper way to obtain a description of muscle coordination patterns during human walking. On the basis of this information we can answer the fundamental question about the onset and offset times of muscle activity. Besides, having also muscles length profiles we can assume the contraction level of muscles. That is why the purpose of our study was to determine timing of the muscle activation patterns and joints angular motion in the lower extremities during gait in able-bodied. METHODS All data were collected in the Biomechanics Laboratory of the Faculty of Sport Science (Bologna, Italy). The subjects of the study were 3 adults: (2 women and 1 man) between 23-33 years old. Inclusion criteria aimed at selecting only subjects without any locomotor’s disorders: no history of orthopedic or neurosensory disorders that would affect the results of the study. Gait cycles with normal stabilized velocity for each subject were recorded. The study was based on the mean values of angle ranges in sagittal plane in the following joints: ankle joint, knee joint and hip joint; changes of the muscle lengths (Rectus and Biceps Femoris) and their electrical activity. Kinematic data Eighteen spherical markers, 14 mm in diameter were attached to the subject’s body with double-sided tape according to PlugInGait model. A Vicon system (Vicon 460) that consists of strobe, infrared light and six cameras operating at 120 Hz, was used to capture the 3D kinematic data. Subjects walked on a 6 m walkway. All subjects were tested in one session encompassing three trials at a self-selected (natural) speed. Prior to data collection, the following physical measurements of the subjects were recorded: height, weight, left and right leg length, left and right knee width, right and left ankle width. EMG Data Proper EMG signal requires respecting some rules. In order to achieve the right placement of the electrodes and to lower the level of artefacts (electrical interference) and noise we followed “Seniam” recommendations (www.seniam.com). As the type of electrodes depends on the investigation, in our study – like in most kinesiological studies, surface electrodes were applied as they are non-invasive. Proper skin preparation is very important to improve the electrode-skin contact and better EMG recordings simultaneously. That is why we shaved the hair from the area of our interest, then the skin was cleaned with alcohol and dried. Afterwards we used Ag/AgCl surface circular electrodes (diameter 10 mm distance 3 cm). The activity of four muscles (bilaterally Rectus Femoris (RF) and Biceps Femoris (BF)) was studied during walking with natural speed. Amplified EMG signals were collected by the Noraxon Tele Myo 2400R with high pass filters set to 10 Hz +/- 10% cut off. The raw EMG signal was processed by filtering (High pass filter 20Hz), rectification, filtering (Low pass filter 25 Hz). The accuracy and validity of any Onset/Offset calculation depends on an appropriate threshold definition. Several methods can be applied to define the onset and offset of muscle activity. In our study determined it using the visual method. It was a result of our previous investigations focu...

EMG profiles during able-bodied walking

MERNI, FRANCO;PECORAIOLI, FABRIZIO;
2009

Abstract

Locomotion is the general definition of all the movements that cause transferring of the body weight. Normal bipedal gait is the most common human activity that is achieved due to the coordination within changes of mutual body segments displacement and muscles work. Systematic study of walking confirmed its complex nature that apparently seems to be very simple. Current technology involving more sophisticated and advanced instruments permits dynamic recording of many specific gait characteristics. In recent years surface electromyography (EMG) has become an important toll in establishing the role of muscles in the specific activities. The first recording of this electrical activity was made by Marey in 1890, who also introduced the term “electromyography” [1]. This method is a proper way to obtain a description of muscle coordination patterns during human walking. On the basis of this information we can answer the fundamental question about the onset and offset times of muscle activity. Besides, having also muscles length profiles we can assume the contraction level of muscles. That is why the purpose of our study was to determine timing of the muscle activation patterns and joints angular motion in the lower extremities during gait in able-bodied. METHODS All data were collected in the Biomechanics Laboratory of the Faculty of Sport Science (Bologna, Italy). The subjects of the study were 3 adults: (2 women and 1 man) between 23-33 years old. Inclusion criteria aimed at selecting only subjects without any locomotor’s disorders: no history of orthopedic or neurosensory disorders that would affect the results of the study. Gait cycles with normal stabilized velocity for each subject were recorded. The study was based on the mean values of angle ranges in sagittal plane in the following joints: ankle joint, knee joint and hip joint; changes of the muscle lengths (Rectus and Biceps Femoris) and their electrical activity. Kinematic data Eighteen spherical markers, 14 mm in diameter were attached to the subject’s body with double-sided tape according to PlugInGait model. A Vicon system (Vicon 460) that consists of strobe, infrared light and six cameras operating at 120 Hz, was used to capture the 3D kinematic data. Subjects walked on a 6 m walkway. All subjects were tested in one session encompassing three trials at a self-selected (natural) speed. Prior to data collection, the following physical measurements of the subjects were recorded: height, weight, left and right leg length, left and right knee width, right and left ankle width. EMG Data Proper EMG signal requires respecting some rules. In order to achieve the right placement of the electrodes and to lower the level of artefacts (electrical interference) and noise we followed “Seniam” recommendations (www.seniam.com). As the type of electrodes depends on the investigation, in our study – like in most kinesiological studies, surface electrodes were applied as they are non-invasive. Proper skin preparation is very important to improve the electrode-skin contact and better EMG recordings simultaneously. That is why we shaved the hair from the area of our interest, then the skin was cleaned with alcohol and dried. Afterwards we used Ag/AgCl surface circular electrodes (diameter 10 mm distance 3 cm). The activity of four muscles (bilaterally Rectus Femoris (RF) and Biceps Femoris (BF)) was studied during walking with natural speed. Amplified EMG signals were collected by the Noraxon Tele Myo 2400R with high pass filters set to 10 Hz +/- 10% cut off. The raw EMG signal was processed by filtering (High pass filter 20Hz), rectification, filtering (Low pass filter 25 Hz). The accuracy and validity of any Onset/Offset calculation depends on an appropriate threshold definition. Several methods can be applied to define the onset and offset of muscle activity. In our study determined it using the visual method. It was a result of our previous investigations focu...
2009
New Ideas in Fundamentals of Human Movement and Sport Science: Current Issues and Perspective
92
96
Forczek W.; Merni F.; Lyakh V.; Pecoraioli F.; Perretta N.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/74580
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